Evaluating the efficacy of accent transformation is important when localising speech-enabled software. However, perceived accent is an attribute assigned by a listener, and the apparent success of accent transformation will vary with the audience. Here we show the extent to which evaluations can be affected by audience familiarity with an accent. A perceptual study comparing two approaches to accent transformation is presented to two audiences with differing familiarity with the target accents. For mean opinion score style evaluations, we quantify the approximate change in perception, and show that this can be sufficient to alter relative successfulness of such systems.